| dc.description.abstract | The accurate prediction of rotordynamic behavior of centrifugal pumps has increased in importance over the last decade, with a steady increase in speed and power concentration. Designing a pump which has acceptable vibration characteristics when new is not sufficient. As various publications indicate, it is mainly wear of internal pump annular seals which lead to vibration problems of originally smooth running units [1, 2, 3, 4, 5, 6]. The calculation of pump vibrational behavior is an important element in establishing maintenance intervals to ensure reliable operation. While the mechanical rotor system and boundary conditions at journal bearings can be modelled quite accurately, interaction forces within the hydraulic part of the pump are not well known. Impeller interaction is one important influence on rotordynamics. However, these forces are not sensitive to internal wear. Impeller interaction is treated by several authors [7, 8, 9]. Reliable dynamic modelling of annular seals is established within centrifugal pumps. Measured results of a full scale test machine are presented and used to conform the newly developed, improved model. The overall influence of a change in seal design from smooth to serrated is shown. Additionally, it is demonstrated why the effect of wear deteriorates vibrational behavior and leads to the requirement of periodic internal seal replacement. | en |
